SPL Passeq - Passive Mastering Equalizer

The Passeq is a classic design with passive coil filters and perfectly fulfills the highest expectations in all areas of audio processing, from recording and mixing to mastering and playback.
The superior sound qualities and musical characteristics of passive filters ideally meet increasing demands in creating manifold sound colors full of character. In the HiFi domain, the Passeq is the high-end EQ beyond doubt – a perfect tool to solve room acoustical problems by the turn of a knob or improve the sound of old, or inferior, sources.

With 72 passive filters per channel (36 x Boost, 36 x Cut), the Passeq surpasses all previous designs of this type by a wide margin. Each channel is divided into three Cut and three Boost bands, each offering 12 switchable frequency ranges. The Cut and Boost ranges are not identical; crossovers are designed to work with like a precise mechanic cogwheel so as to allow the engineer access to the largest possible number of optimal, wide-band S-curves with variable slopes.

A further remarkable Passeq feature is its individual sonic adaptation of each inductive filter through separate coil/condenser/resistor combinations: In stark contrast to earlier filter design and construction, each Passeq filter is optimized for the frequency assigned.
To insure the best possible signal warmth, richness and musicality in processing, coils for critical voice frequencies are custom-made for the Passeq.
This achieves the widest possible range and tonally appealing sound color palette from any passive EQ.

The most powerful passive EQ ever made—144 (!) passive filters (72 per channel) in one EQ.

Individual coils per filter.

Single core coils, which means that every one is wound individually on its own dedicated core. This excludes sonic degradation from mutual influences while at the same time improving THD values.